1. Field of the Invention
This invention relates to anhydride-functional polymers obtained by at least partially hydrogenating an unsaturated polymer which was obtained by reacting, under ene reaction conditions,
(i) an unsaturated anhydride having the structure: ##STR2## wherein R.sub.1 and R.sub.2 are each independently hydrogen, alkyl of 1 to about 6 carbons, or alkoxy of 1 to about 6 carbons, or a halogen; and PA1 (ii) at least one polyolefin having at least two carbon-carbon double bonds in the polyolefin backbone and having an average of at least three carbon atoms in the polyolefin backbone between the carbon-carbon double bonds. PA1 (a) a basecoat comprising a pigmented film-forming polymer; and PA1 (b) a transparent clearcoat comprising a film-forming polymer applied to the surface of the basecoat composition;
The polyolefin which is reacted under ene reaction conditions with the unsaturated anhydride will have an average of at least three carbon atoms in the backbone between the carbon-carbon double bonds. The backbone of such a polyolefin would be comprised primarily of repeating units having the structure: EQU --[--(CR.sub.3 R.sub.4).sub.x --CHR.sub.5 --CH.dbd.CH--]--
wherein each x is individually a number from 2 to about 15; and R.sub.3, R.sub.4 and R.sub.5 are each individually hydrogen, or a linear, branched or cyclic aliphatic group of 1 to about 18 carbon atoms. By "primarily" is meant that at least 60% by weight, and preferably at least 90% by weight, of the repeating backbone units of the polyolefin would have that structure.
The preferred polyolefin has the structure: EQU Z--CH.dbd.CH--[--(CR.sub.3 R.sub.4).sub.x --CHR.sub.5 --CH.dbd.CH--].sub.n --Z
wherein each x, R.sub.3, R.sub.4 and R.sub.5 is as defined above; each Z is individually hydrogen, or a linear, branched, or cyclic aliphatic group of 1 to about 36 carbons; and n is a number between 2 and 5,000.
Between 1% and 100%, and preferably between 20% and 95%, of the carbon-carbon double bonds of the unsaturated polymer obtained by the ene reaction will be hydrogenated to produce the hydrogenated anhydride-functional polymers. The hydrogenated anhydride-functional polymers should have an average of at least two anhydride groups per molecule. As used herein, the term "hydrogenated anhydride-functional polymer" means a polymer in which at least 1% of the carbon-carbon double bonds have been hydrogenated.
The hydrogenated anhydride-functional polymers are useful as corrosion or scale inhibitors, thickeners, dispersants, and as reactive agents and/or crosslinking agents for compounds having functional groups, such as epoxy, hydroxyl or amine groups, which are reactive with anhydride groups. The hydrogenated anhydride-functional polymers can, therefore, be utilized in a variety of materials such as plastics, fibers, adhesives, paper sizing, inks and, particularly, coating compositions.
This invention also relates to novel reactive compositions which utilize the hydrogenated anhydride-functional polymer in combination with one or more materials which can react with anhydride groups. These reactive compositions can be reacted at room temperature or force dried at temperatures ranging up to about 350.degree. F. or higher if desired. When utilized as reactive crosslinking agents for coatings, the hydrogenated anhydride-functional polymers may be utilized in a variety of coating applications, including primers and topcoats as well as clearcoats and/or basecoats in clearcoat/basecoat compositions.
The reactive compositions typically involve the combination of the hydrogenated anhydride-functional polymer with materials reactive with anhydrides such as polyepoxides, polyamines, polyols, etc. One preferred reactive composition comprises the hydrogenated anhydride-functional polymer and a polyol, preferably a hydroxy-functional polymer, optionally in combination with an epoxide or polyepoxide. Another preferred reactive composition comprises the hydrogenated anhydride-functional polymer, an acid-functional compound, an epoxide or polyepoxide, and, optionally, a polyol. All of these combinations can provide fast reacting, durable coatings which minimize the toxicity problems which may be associated with other low temperature curing systems.
2. Description of the Prior Art
Some polymers obtained by the reaction of unsaturated anhydrides and olefins are known in the art. Japanese examined patent application number 48-43191 teaches the Ziegler-Natta copolymerization of alkenyl anhydrides with olefins such as ethylene, butene or styrene, in the presence of a mixed catalyst comprising an organic metal compound and a transition metal compound. U.S. Pat. No. 4,374,235 teaches polymers obtained by the free radical initiated addition polymerization of an alkenyl succinic anhydride with one or more vinyl monomers such as maleic anhydride, maleimides, vinyl acetate, and alkyl vinyl ethers. U.S. Pat. No. 4,599,432 teaches the production of alkenyl succinic anhydride compositions by the reaction of an olefin and maleic anhydride followed by the addition of a free radical catalyst to polymerize any unreacted olefin and maleic anhydride. U.S. Pat. No. 4,927,868 teaches resinous binders obtained by the free-radical initiated copolymerization of an .alpha.-olefin or cycloolefin and an olefinically unsaturated monoanhydride. U.S. Pat. No. 4,720,555 teaches hydrocarbons substituted with at least two anhydride moieties produced by the free-radical initiated copolymerization of a specified hydrocarbon and a molar excess of an organic anhydride. U.S. Pat. No. 5,066,742 teaches the free-radical addition copolymer of a C.sub.2 -C.sub.8 olefin and maleic anhydride as an aqueous copolymer suspension.
The ene reaction involving unsaturated anhydrides with certain olefins is also known in the art. U.S. Pat. No. 4,026,867 teaches resinous condensation products made from (i) the ene reaction adduct of an unsaturated anhydride or acid or ester thereof, with a specified unsaturated liquid phenol or oligomer thereof, and (ii) an aldehyde. U.S. Pat. No. 4,107,114 teaches the ene reaction of maleic anhydride and unsaturated polyolefins such as polypentadiene. The resultant anhydride-functional polymer can be subjected to a ring cleavage reaction to produce an acid-functional polymer. U.S. Pat. No. 4,396,774 and 4,736,044 teach the ene reaction product of an unsaturated dicarboxylic anhydride and an ethylenically unsaturated hydrocarbon in the presence of a Lewis acid catalyst or a specified boron compound, respectively. U.S. Pat. No. 4,927,669 teaches the ene reaction of maleic anhydride with unsaturated fatty acids. U.S. Pat. No. 4,919,925 teaches the ene reaction product of .alpha.-olefins and unsaturated anhydrides in the production of deodorizing compounds.
Unsaturated anhydrides, such as maleic anhydride, and copolymers made from maleic anhydride are known in the art. Such anhydride copolymers are heterogeneous with respect to the distribution of anhydride groups along the backbone of the polymer due to the abnormal copolymeric on behavior of maleic anhydride with other monomers, and the acid groups generated from opening these anhydrides by reaction with hydroxyl or amine groups are not highly reactive for further cure reactions, e.g. with epoxy groups, due to steric hindrance arising from the proximity of the anhydride ring to the polymer backbone. Such anhydride-functional polymers are also relatively viscous and may be difficult to utilize in combination with low levels of solvent. Additionally, such polymers may form dark colored materials when certain base catalysts, such as N-methyl imidazole, are used to accelerate a subsequent reaction of the polyanhydride with reactive materials such as hydroxy-functional compounds.
Curable compositions comprising polyanhydrides in combination with other reactive materials are also known in the art. For example, U.S. Pat. No. 4,946,744 teaches clearcoat/basecoat combinations involving (i) a polyanhydride, for example, such as that prepared by copolymerization of maleic anhydride with (meth)acrylic monomers, and (ii) a polyol. U.S. Pat. No. 4,871,806 teaches curable compositions comprising a polyanhydride, a polyacid, a polyol and an epoxy-functional compound. U.S. Pat. No. 4,859,758 teaches an acid-functional cellulose ester based polymer which could be used in combination with a polyanhydride and a polyepoxide.